Automatic telephone system



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H. M. FRIENDLY AUTOMATI C TELEPHONE SYSTEM Filed Aug. 22, 1924 5 Sheets-Sheet 5 Inv anim"- g Herb Erl-PJ-Frendlg 5, Mm l A uu Patented Apr. 30, 1929.

UNITED STATES.

HERBERT M. FRIENDLY,' OF CHICAGO, ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed August 22, 1924. Serial No. 733,460.

' rarily interconnect-ed by remotely controlled switching mechanism.

rlhe organization chosen to elucidate the invention comprehends a multi-office twowire Strowger automatic or machine switching telephone system wherein five digits, or the equivalent, comprise the numbers of the respective called lines. It will be understood that the number of digits employed in directively establishing a connection between lines may be varied; five digits being taken for the exampled system, as in general, commercial exchange operation this is the smallest number employed for multi-office systems. Theinvention is applicable to other types of line switching systems.

An object of the invention is to enable a switch, corresponding to a first numerical switch (as a so-called first selector in the exampled system), to have direct access to one or more groups of outgoing inter-office trunk lines leading to respective remotely located ten-thousand groups or offices of the system as has been a well-known practice. The respective said trunks of the group or groups terminate in socalled incoming second selectors. The said first selectors also have direct access to groups of local trunk lines; each latter said trunk line leading to -a socalled local third selector (such as selector FSsshown in the present application), located in the same oflice as the said first selector. That is, certain levels of the said first selector will contain respective groups of interoffiee trunks leading to ten-thousand line groups of the exchange system numerically designated to correspond to the level position from which trunks lead from the first selector bank, andfrom other levels of the said first selector, groups of local trunks lead to so-called third selectors (having the second higher numerical order value with re ference to 'the first selectors) in the same office as contains the firstselector; all levels of bank contacts of the first selector being swept by the same set of wipers commonly.

Another object of the invention is to admit of employing all the levels of the first selector' while at the same time precluding' calls being vitiated by a so-called preliminary or false impulse or series of impulses wh'nxh may be applied inadvertently before the directing 4dial is initially operated. Such false operation will be prevented from causing the call being progressed to a wrong called line, because the first selector will be thereby disabled against thereafter selecting until the call is terminated. The bank levels of' the first selector from which the inter-office trunks lead are chosen vabove the first'or lowermost level. In the present exampled system, the second level is the lowest level used for inter-office trunks. However, it is preferred to have the third or a higher level as the lowest level used for inter-ofiice trunks, as any possible initial false impulse or series constituting a first digit af'ter initiating the call by the removal of' the receiver from the switch-hook, and before directively operating the dial, should be effective to disabling the call from being extended.

u The larger the range of said false impulses impossible of' introducing an erroneous call the more effective the arrangement becomes. Thatlis, 1f the second level is the lowest one used forinter-ofiice trunks, and a false series of two impulses is accidentally introduced by a careless movementof the switch-hook while removing the receiver, the Wipers of the first selector will be caused tof align 4with the second level andthere rotate-in and select an inter-ofiice trunk leading to an incomlng second selector in the 2 ten-thousand group. Then, when the calling party directively annexes the five digits of the called line number, the first digit sent will be effective to operate the incoming second selector of the 2 ten-thousand group, a number being reached responsive tol the sending of the fourth digit which is not the-one intended to be called; the fifthdigit sent being idle so 'far as yany linking operation is concerned. This false impulsing sometimes manifests itself when a line becomes crossed and then momentarily clears. Under the latter condition it will progress a connection to an accessible local or an accessible incoming selector', depending upon the number of impulses introduced, idly holding such seized selector; in fact, a train of'switches may be thus interlinked.

It will be manifest that the probability for a false single impulse will be greater than for a false series of two, three, vand more impulses,

in the inverse relation to the number of iinpulses; at least this is borne out in practice.

All levels of the first selector not used for inter-office trunks may be used for local trunks to .local third selectors of the ten-thousand lll) `group containing the concerned first selector'. ln general, it the first selector is not primarily operated to a level corresponding to a tenthousand groul'i. the selector will be disabled and a sustained tone applied to the calling line indicative of the condition to prompt the calling party what has occurred, so that he may hangl up the receiver to restore the first selector' and then initiate a new call. 'lfhc prompting tone thus serves to educato the subscribers to the more careful removal of the receiver or the more careful handling of switching plugs or keys, where a jack and operatoris switchingl plug or a key is used in place oit a telephone and switch-hook.

vlt' the bank level with which the wipers ot` the first selector have been operated into alignment has the runnerically corrt-fsponding level position with the numeral indexing the ten-tl'iousand group containingthe concerned first selector, the .shaft ot the first selector will be thereupon caused to rcstore to normal and prepared to operate rotarily so that when the said first selector ot the connection is re-operated vertically with relation to a. level corresponding numerically with the second digit of the called line located in the ten-thousand group containing the concerned first selector, the wipers ot'the first selector will be automatically rotated in hunting` relation and seize a local trunk leading to a local third selector, in readiness tor next operating the said third selec-tor by way of extending the Call to the vconnector, in the direction of the called line.

rlhe call to a line ot the ten-thousand group containing the concerned lfirst selector will route 'from the first selector to the local third selector responsive to the second digit vthen through the third selector to the connector responsive to the third digit, and through the connector to the called line responsive to the last two digits. However, if the call is to a line of a ten-thousand o'roup reached over an inter-office trunk, the first selector extends the call overan inter-office trunk to an incoming second selector of the ten-thousand group containing the called line, responsive to the first digit, so'tliat the second digit will operate'said second selector to seize a trunk local to it extending to a third selecfor. The third digit will operate the third selector to seize a trunk to the conl'iector; the last two digits then operating the connector to .set its wipers on the terminals ot the called line; completing the onncction.

'.lhe first selector will preferablyhave ten levels corresponding to the digits 1 to (l, so that any level. or levels oit the first selector' not corresponding to a ten-thousand group or groups other than the ten-thousand group to which the mncerned first selector belongs may refer to a thousands group ot the tenthousand group to which the concerned first selector' belongs. That is, if the system, as

exampled, which has three ten-thousand groups, eight levels of the concerned first selectors of the present invention will be available for local trunks to eight thousands groups of local third selectors. '.lhe first selector level numerically7 corresponding to the first digit ot the calling number ot' the ten-thousand group containing the concerned first selector' may thus have local trunks extending to a numerically corresponding thousands group, each trunk ot which terminates in a local third selector. The' ultimate capacity of a ten-thousand group employing first selectors ot the present invention having three ten-thousand groups comprisingl the system is thus eight thousands groups, or eight thousand lines ultimate capacity. It' the system should contain four ten-thousand groups, each ten-thousand group employing first selectors of the present invention would have an ultimate capacity of seven thousands groups. However, where an ultimate capacity of ten thousands is desired from the ten levels, the particular ten-thousand group will have local second selectors introduced between the first selectors and local third selectors, as in general, well known practice.

An object of the present invention,.in general, is to guard the system against wrong number calls resultant :from careless operating by the calling party. For instance, the false or preliminary digits adverted to, as well as the condition wherein the calling party sends a digit series too soon after an antecedent series to admit ot the last selectorI operated with relation to a level to complete its` limiting operation thereat.' The present invention provides means for disabling a selector against seizing' a trunk it the calling lOl) dial is operated while the selector is hunting,

and to apply a prompting tone to the calling party indicative of the condition. Only the usual relays of theoselcctor are employed in carrying out this function. It the calling party then ignores the said prompting tone and proceeds to annexthe series constituting the unsent digits of. the called number, the saiddigits will be to no operative effect. It will be necessary to terminate the call to restore the operative condition ofthe selector. Reference is madeto my Patent No. 1,506,054, granted Aug. 2G, 1924. `l

Reference is also made to my pending applications Serial No. 171,637, filed Majv 2S), 1.917, and Serial No. 362,321., filed March 1, 199.0. It is intended to claim the broader aspects of the subject matter common to these prior applications and the present application in the relationship of the respective filing dates. That is, only subject matter not disclosed in either of these earlier pending applications is intended to be claimed in the present application, althougl'i there is subject matter claimed in the said prior pending ap- Cil plications that is disclosed but not intended to be claimed in the present application.

Another object of the present invention is to afford a first selector which in addition to the objects set forth, enables one or more levels thereof to refer to respective thou sands of remotely located thousands groups. 'lhis will reduce the local thousands capacityot' the first selector correspondingly. For example, the system (as exampled herein) comprises three ten-thousand groups wherein eight levels are available for local use, any number ofthese so-termed local levels may have the trunks thereof extended outside of the containing building to incoming third selectors yin, a remotely located buildilw. However, in commercial operation, it would usually be preferred to have the calling` -numbers of the subscriber lines tributary to said remotely located building' have a. different index or first digit, so that in the event the connected capacity outgrows the eight levels of the first selector, thesaidremotely located building will contain numbers reached over inter-office trunks specifically indexed by the first digit. To avoid havin-g to change the calling numbers of lines tributary to said `remotely located building, the present invention contemplates that a specific index digit refer to these lines. That is, in the present exampled system, pulling either digit 4t or 5 initially will operate and then release the first selector and prepare/the first selector to select in'any level alotted to trunks leading to local or to remotely located third selectors. `In the present exampled system, the first level of the first selector refers to local third selectors and the fourth and the fifth levels refer to lremotely located (incoming) third selectors. Manifestly, levels from the sixth to the O level inclusive can be chosen at random for trunks extending to local or remote third selectors, wherein pulling either digit 4 or 5 first will prepare the first selector to select a trunk of any level other than the second and third (used for inter-office trunks to incoming second selec-v tors) responsive to the second digit pulled. 'll`hus,'pulling digits 45 or 55 will cause the first selector to select in the samelevel and extend the call in the direction of the same line, determined by the last three digits. rlhis arrangement permits two or more tenthousand groups to be contemplated and numbers permanently assigned in accordance therewith wherein one or more (two in the present instance) thousand groups will be temporarily operated as subordinate to one of the ten-thousand groups and wherein the inter-office trunks of the latter said ten-thousand groups will also directly serve the thousand groups subordinate thereto. This arrangement thus effects a saving in equipment through the elimination of the incoming second selector in the building containing the sub-groups, since the trunks leading from the first selectors of themain group lead directly to incoming third selectors in the building to which thesub-group subscribers are tributary. At such time as itis found desirable to make the sub-group a main group," incoming second selectors will ha: installed antecedent to the incoming third selectors (thereafter operating as local third selectors) and direct inter-office trunks from the respective lnain offices of the system terminated therein. Local first selectors like F S, F53 or FS will then be installed in the converted sub-office for originating traffic as conditions warrant, in view of descriptions to follow.

Outgoing traffic from a sub-office may be handled independently of the incoming traffic, using methods wellknown,"considering the sub-ofiice as a. `so-called satellite office as to outgoing traffic therefrom, wherein a set of trunks therefrom to a main office of the` system is provided, or wherein a direct outgoing inter-ofiice trunk group to each of the main offices is provided.

Another object of the present invention is the means for prompting the user of a busy called line when a call thereto has been selectively lmade and barred by reason of encounteringthe called line busy. A briefly applied tone or battery click, or both, to the called line denotes to the user of the called line that connection thereto has been sought.

i Under the condition, the connection will be terminated as soon as expedient so that the line will probably `be found free upon a new attempt to connect with it shortly thereafter. This conducestoward reducing the'average holding timeof connections, which in turn, reduces the number of connecting links required for handling a given number of calls per unit of time. Reference is made to my U. S. Patent No. 1,506,054, granted Aug. 26, 19:24, which discloses a connector with a generally similar object, as well as other de- 4vices outside of the connector Ioperated by the connector, having a generally similar object. It will be noted, however, that in the present instance the automatically applied means in the connector applies the tone to the busycalled line responsive to encountering the busy condition, and not means in the connector operative responsive to the calling party restoring hisI receiver, as in the citation. rlhe connector of the present invention does not require additional relays in carrying out this function.

ln view of the foregoing genera-l remarks, it will be manifest that the present invention may be employed in a system wherein ten-thousand groups are not equipped with third selectors to the ultimate ten-thousand capacity, gaining the saving of the local second selectors.- The concerned ten-thousand group may then be subsequently changed to employ local second selectors at such timev Cil as it is desired to increase the number of lector from limiting over a level corresponding to local third selectors responsive to the first directed digit series. llhe object of this function is to preclude a wrong subscribers line being called, in the event the calling party carelessly omits the first digit., or omits the letter or name prefix corresponding to the first digit of the number under call. For instance, assume that in the present exampled system a call is made from a line tributary to the 4l ten-thousand group to called line number Main-1562, wherein Main corresponds to digit 3. Assume further that the calling party neglects to pull the calling dial in -correspondence with the prefix Main and therefore pulls the first numerically indicated digit 1. The first level of the first selector corresponds to local trunks leading to third selectors represented by third selector B. However, it will appear presently that the first selector will not be enabled to rotate-in on the first level unless the dial has been pulled with correspondence to digit 4, which latter digit indexes the containing ten-thousand group. lf this function were not provided, the call would be extended to line 1562 in the 4; ten-thousand office, thus annoying a subscriber not wanted as well as creating the impression in the mind of the calling party that the apparatus functioned improperly. The function last referred to contemplates means for disabling the first selector and applying the prompting` tone audible to the calling party if the first digit sent Adoes not index a ten-thousand group. Further, unless five digits are sent, the call cannot be completed to any line, so that if the calling party omits the first digit (or corresponding prefix) and the numerical value of the second digit indexes a ten-thousand group by coincidence, the call will be progressed towards lines embraced by the last four digits of the number when the said four digitsare employed as the first four digits, andwill not reach a subscribei" s line due to lacking the fifth digit to set the final switch upon a subscribers line. Generally stated, if the first digit (or its equivalent) sent does not index a ten-thousand group, the first selector will be disabled from limiting lover a level group of trunks, and therefore', if the first digit indexes a level of the first selector which corresponds to a group of local third selectors, the first selector will be thereupon disabled from hunting over the corresponding level group. Or it may be otherwise stated that if the first digit sent does not index the ten-thousand group containing the calling line or another ten-thousand group, the concerned first selector will not be enabled to perform a rotary movement at the level attained responsive to the first digit. If the level attained indexes the ten-thousand group containing the first selector, it will restore preparatory to being reoperated to a level at which it will automatically initiate its yhunting movement. nd if the level attained indexes an inter-office trunk level group the concerned first selector will thereupon hunt thereon to extend the calling line to an incoming second selector in the ten-thousand group or office indexed by the first digit.

'l` he invention has other objects and applications than specifically mentioned. Its scope, as applied to automatic line switching systems in general will be defined by claims annexed.

With reference to the accompanying five sheets of drawings: n

Fig. 1 shows a calling telephone C'l leadino to a line switch LS, the latter having ac-v cess to a first Vselector FS of the present invention. The line switch LS and thefirst selectors FS are located in the si ten-thousand group, and the first selector FS has access to local third selectors A and B in said Fig. l, and to incoming second selectors C and D in Figs. 2 and 3, respectively.

Fig. 2 shows a portion of a first selector FS2 (of the present invention), which is like the first selector FS, excepting as to the use of a wiper connected to conductor o (corresponding to conductor a); and bank contacts attached to conductors b and c y (corresponding to conductors Z) and c, respectively). The first selector FS2 is located in the 2 ten-thousand group and has access to local third selectors E, F and Gr in said Fi 2 and to incoming second selectors H and I in Figs. l and 3, respectively. The first selector FS2 bears thel same relation to a line switch (not shown) and calling telephone and line (not shown) as does the first selector FS; the missing conductors and elements of selector FS2 being understood as disposed like conductors and elements shown in first selector FS,

Fig. 8 shows a well known selector FS, modified in accordance with the/present invention by the introduction of the rotary offnormal contacts, the tone source and the armature and connections of the series relay. lt is accessible from a calling telephone .T3 through the line switch LSS. The first selector FS3 is located in the 3 tcn-tluuisaml group and has access to local second selectorn in said Fig. .3 and to `incoming second selectors K and L 1n Figs. 1 and 2, respectively.

l Fig. 4 shows a preferred modification of the lower two shaft-controlled contact sets shown in Fig. 1.

Fig. 5 shows first selector FSS, which isa preferred modification of first selector FS.

Fig. 6 is a well known connector C", modified in accordance with the present invention. Incoming third selectors W and X are reached over trunks fw and w, respectively, and they have access to connectors Z and C, respectively.

With further referenceto the drawings, the incoming second selectors H and K in Fig. 1; local third selectors A, A, B and M in Fig. 1; incoming second selectors C and L in Fig. 2; 'local third selectors F, G, G, 4N and E in Fig. 2; incoming second selectors D and I in Fig. 3; local second selector J in Fig. 3; local third selector P in Fig. 3; incoming second selectors H and K in Fig. 5 ;local third selectors B and M in Fig. 5; and incoming third selectors IV and X in Fig. 6 are to be assumed as representingselectors like FS3. Connectors Q and R in Fig. 1; S, T and U in Fig. 2; V n-Fig. 3; R in Fig. 5; and Z in Fig. 6 are like connector C6 in Fig. 6. The telephone CT, T and T in Fig. 1; T2, T2 and T2 in Fig. 2; T3 and T3 in Fig. 3; T5 and T5 in Fig. 5; and T6 and T6 in Fig.` 6

are well known automatic telephones ofthe series type. The line switches LS, LS3, LS5 v and LS`are well known line switches or finder switches.

First selector' FS is likethe first selector FSB, excepting for certain changes with reference to the verticalmagnet circuit; socalled interrupter relay circuits; shaft-operated contact sets; contacts operated by the so-called release double-dog mechanism, as kwell as the employment of a vertical off-nor Inal tone source applied through armature'of the socalled series relay y'and a shaft-operated contact set. i

`First selector FSf is like first selector FS,

excepting for the wiring of the so-calledseries relay and the device for applying interrupted ground to Vmaintainthe said relay locked. V(,)ftherdeta'iledchanges inselector F S5 will be discussed presently. l

`Connector C in-Fig. 6 is generally like the connector shown on page 38 of the book Automatic Telephone Practice, third edi-1V tion, by Harry E. Hershey, and also shown in Fig. 7 of my pending application for U. S. Patent Ser. No. 535,430, filed Feb. 10, 1922. However, a modification in accordance with the present invention involves the apprising tone source and the uppermost sets lof contacts on relays B and A and the uppermost resting contact of relay W, as will be discussed 1 presently.

The inventionv will be comprehended from the following description of assumed calls in the exemplary system.

The sheets containing Figs. 1, 2 and 3 are to be placed one below the other vin numerical l ing of line relay 101, armature 102, conductor 103, wiper of line switch LS, telephone CT, conductor 105, armature 106, lower winding of relay 101 to ground, causing relay 101 to actuate, operatively ener izingslow-releas-- ing relay 108 to groun ed conductor 109 to maintain the line switch LS. Upon the calling party operating the calling device 11'2l in correspondence withthe first digit 4, the armature 113 'will correspondingly vibrate four times to apply its ground through armature 114, sustained armature 115, vertical off-normal (VON) spring 116, slow-releasing series relay 117 to the vertical magnet, designated Vert. M. This willcause the shaft SH carrying wipers 118 to 120 to be set into alignment with the fourth level of bank contacts, having inmind the attracted lower armature of relay 117 will maintain the circuit to the vertical magnet closed after the spring 116 has disengaged consequent to the off-normal movement of the shaft SH.

In this connection, it will be understood that spring-set 121 closes only while the wipers 118 to 120 are in alignment with the fourth level of bank contacts; operated by a project-ion d of the shaft, having in mind that the first selector FS is located inthe 4 tenthousand group. The-sprirtg-set 121 opens upon the shaft rotating-in. It will thus appear that upon relay 117 deactuating', after the last said impulse to the vertical magnet, a circuit path can be traced from grounded conductor 109, armature 122, upper set of 'vertical od-normal springs, conductor a, springset 121, conductor b, armature 123, lower set of vertical off-normal springs, to the release magnet, designated Rel. M. The release magnetrwill operate its armature c to restore the shaft and tooperate the well known so-called double-dog 124 and lock it againstretracting under the influence of spring 125, through the agency of the well 4known so-called re lease-link 126. The setuof springs 127 H6129 is operated by the vdouble-dog V124,so that spring 127 is normally in engagement with spring 129, while spring 128 is normally disengaged, at which position the release link 124 tion.

In this connection, it will be stated that the double-dog 124, retract-ile spring 125, release.- link 126, and projection 130 correspond to parts bz2, Z22, f7 and 523 in lFigs. 16 and 17 of U. S Patent No. 815,321, granted to A. lil. Keith and d'. and C. J. Erickson, March 13, 1906. The mechanical structure of the selectors of the present invention correspon d generally to the structure disclosed in the said patent, modified, of course, to operate in accordance with the so--called `two-wire principle and in accordance with the present inven- The drawings with reference to the double-dog mechanism, do not purport to disclose the exact mechanical structure, they being simply schematic in order to make the disclosure as simple as possible, but the structure contemplated will be fully understood, inview of the said citation,

It will be thus clear that at the time the release magnet operates its armature e, consequent to the establishing of its described energizing circuit, the spring 117 will disengage from spring 128 and engage spring 129 before the upper set of vertical olf-normal springs open, since the shaft SH has not yet had time to restore. That is, ground will lbe applied from conductor 109, armature 122, upper set of off-normal springs, springs 127129 to the winding of relay 132 to operatively energize the latter said relay and lock it through armatures 134, 135, 136 to grounded conductor 109 before the shaft has had time to restore to normal. A circuit for the rotary magnet is thus prepared at armature 139, but which is open at spring 128, and this circuit is maintained closed at armature 139 due to the locked condition of relay 132, dependent vupon the conductor 109 remaining grounded while the shaft remains at normal, and thereafter until certain operations, as will appear presently, occur.

Upon the second digit 4 being sent from the calling device 112, relay 101 will vibrate four times and relay 117 will attract its armatures while the vertical magnetJ` is again raising the shaft so its'wipers are again set to align with the fourth level of bank contacts, the release-link 126 disengaging the projection 130 to allow the double-dog 124 to restore and the spring 127 to disengage from spring 129 and retract against spring 128 consequent to the first operation of the armature f of the vertical magnet. Consequent upon the armature 122 retracting following the fourth impulse to the vertical magnet, a circuit will be closed from grounded conductor 109, armature 122, upper set of vertical off-normal springs, springs 127-128, armature 139 to the rotary magnet, the rotary magnet operating to rotate the shaft one step" from normal, incidentally closing the spring set RON and opening the described locking circuit for the relay 132 at armature 135. Vipers 118 to 120 lare new in engagement with the first set of 118, armatures 142, 135,

bank contacts 141, 144 and 145, respectively,

, of the fourth level.

1f it is assumed that bank contact 141 constitutes busy-ground, applied in the well known manner by a selector (not shown) companion to selector FS, a circuit can be traced from busy-grounthbank contact 141, wiper RON spring set to the winding of relay 132, the latter saidrelay reactuating and locking through armatures 135 and 136 to grounded conductor 109, supplemental to the ground on bank contact 141 applied to armature 135. The before described path from grounded armature 122 to the rotary magnet will now be closed, causing the rotary magnet to rotate the wi pers 1.18 to 120 to the next set of bank contacts, the rotary magnetpagain operating if the wiper 118 encounters a busy-guarded bank contact. llf the wiper 118 rotates into engagement with a bank contact which is not busy-grounded, ground will not be applied to operatively reenergize relay 132. Then, when the armature 136 retracts and the wiper 118 does not receive ground from an engaged bank contact, a circuit can be traced from grounded conductor 109, winding of relay 143, armature 135, spring set RON, winding of relay 132 to grounded battery, the relay 143 actuating to thereby effect the seizure of the selector FS, while the armatures of relay 132, due to its marginal adjustment, remain retracted. Thus, if it is assumed that the w iper 118 did not encounter busy-ground on bank contact 141, the calling line will be extended to third selector A consequent to selector' FS seizing by the actuation of relay 143.

The third selector A will operate in the well known manner, in view of the present invention, as will appear, to seize the connector Q, responsive to the sending of the third digit 2 from the calling device 112, and the connector' Q will operate in the well known manner, in view of the present invention, as will appear presently, responsive to the sending of the last two digits 31'from the calling device 112, to set the wipers upon the called line leading to telephone T. The called telephone T will be signaled in the well known manner, and the selector FS and the line switch LS will be maintained from ground applied back from the connector Q. The call will be destroyed in the well known manner, having in mind that the effective circuits of selector FS are equivalent to those of selector A after its seizure. That is, when ground is removedfrom conductor 109 resultant to the deactuation of the .so-called release relay of the connector Q, the relay 143 will deactuate,

whereupon a circuit can be traced from grounded armature 113, 'armatures 114and 115, lower set of vertical off-normal springs 4to the release magnet, its armature e operating to restore the shaft SH and lock the double-dog 124 into the position shown in the projection 130 cooperating with opening in the release link 136.

The call described was to telephone T belonging to the tenjthousand group to which the calling telephone CT belongs. Itis noted that the first digit 4 was not effective to cause a completed linking operation; it only serving to set-up a specific preparatory condition ,ifn the first selector FS. The second digit 4 effected a linking operation to a local third selectorA, so that but two directive linking switches are required to complete the connection beyond the first selector, whereas five digits are employed, the first digit beingabsorbed, as it were, by the restoration of the shaft of firstselector FS.

It will now be assumed that the calling party inadvertently introduced a preliminary impulse constituting the digit l through carelessly opening the circuit including relay 101 for a brief period by the switch-hook. The Wipers 118 to 120 will vthus be aligned with the first level of bank contacts. However, it will be noted that the set `of springs 121 are not operated to cause the release magnet to restore the shaft and to cause the relay 132 to actuate and lock, as when the shaft was assumed aligned with the fourth level. Under this condition, the rotary magnet will not operate due to the armature 139 being in its normal position. The set of springs 147 (which closes on off-normal vertical positions and opens on rotating-in at all levels) thus remains closed so that tone from the indicated source `in Fig. 1 will be applied through spring set 147 armature 148 to armature 106, audible to the calling party, to apprise him ofthe condition existing, the call bein vitiated. The calling' party lWill replace t 1e receiver, causing relays 101 and 108 to deactuate in sequence to close thedescribed path from armaturev 113 to the release magnet to restorelthe circuits, preparatory for a new call. It will be noted in this connection that if the calling party ignores the said tone and he-then sends the iirst digit 4 of the line under call, no effect will result from the vibration of the armature 113 of line relay 101, due to the vertical off-'normal spring 116 being disengaged and the lower armature of series relay 117 being retracted the vertical magnet being thus disabled. lt Will also be noted that in normal operation, a circuit will be closed from the tone source through Athe spring set 147, armatures 148 and 106 to conductor 105, but the duration of this tone, pending the rotating-in of the shaft SH will be so brief that it Will not cause confusion, and in fact, the armature 148 may be adjusted to retract after armature 122, to reduce the period of application of the tone to conductor 105 under normal operation. Moreover, the brief application of the tonel Will be indicative of the normal operation of the selector FS.

v of the ently.

Had the stated call been to telephone Ti, the telephone number of which is 41321, in lieu of telephone T', the second digit 1 would cause the first selector F S to'have selectively operated as described, but with relation to the first level in lieu of the fourth) to seize third selector B, the call being completed by annexing the last three digits 321,

in the manner before described. The same would apply wherein the second digit refers to a level above the fourth (not indicated), the first, fourth, and all levels aboveV the fourth being reserved for thousands trunks to respective groups of local third selectors; each of said thousands groups indexed by the numerical off-normal position of the level ot' the first selector FS corresponding.

The spring set 151 is adjusted to close when the wipers 118 to 120 align with the second and also the third level of bank contacts; operated by projections h and z', respectively. These latter stated levels correspond to inter-office ten-thousands trunk groups leading to groups of incoming second selectors in respective, numerically corresponding ten-thousand groups other than the one b CT and first selectorF S..

If it is nowassumed that the call was to telephone T2( in the 2 ten-thousand group, the calling number of which is 22341, the first digit sent would be 2, causing the containing the calling line from telephone wipers 118 to 120 to be set into alignment..

with the second level of bank contacts. Due to the said adjustment of the spring setJ 151, when armature 122 retracts, ground from conductor 109 is applied through upper set of vertical off-normal springs, conductor a, spring set 151, conductor c, to the Winding of relay 132, the latter said relay actuating and locking in the manner before described, the armature 139 closing a path from grounded conductor 109, armature 122, upper set of vertical off-normall springs, springs 12T-128 to the rotary magnet. The rotary magnet will thus start the described hunting operation when the wipers .have been set into alignment with the second level of bank contacts, upon the armature 122 `retracting during the saidaligned condition. Tf the first inter-office trunk j of the second level (leading to the 2 ten-thousand group) is idle, the incoming second selector C connected to the said first trunk will be seized thereover, and if the said trunk assumed seized is busy, the first successive idle trunk (not shown) 'of the second level leading to a second selector companion to the said selector C will be seized. The sending of the last four digits 2341 will cause the callto beprogressed Athrough incomingnsecond selector C, third selector N and connector U to the called telehone T2 in the Well known manner in view I.) 5

present invention, as will appear pres ln the last foregoing assumed call, had the first digit been 3, in lieu of 2, the first selector FS would operate as last described, but with relation to the third level, and seize the inter-office trunk it: leading to second selector l), or a trunk (not shown) ot its group. l't the call were to telephone T3', the telephone number ot which is 32321, annexing `the last tour digits 2321 will cause the call to be progressed through said incoming second selector l), third selector l) and connector V to the called telephone 'l"", in the well known manner, in view of the present invention, as will appear presently.

lt will be understood that the single line representing an inter-office trunk may refer totwo conductors or three conductors, depending upon it a repeater or other'` circuit translating device is or is not employed in the trunk. llowever,'tlie inter-oflice trunks are disposed in the well known manner from the banks otvthe fii'st selector FS (and also first selectors FS2, FS3 and FSS). 'lhe local trunks from the banks ot the first selectors FS (and also first selectors FS2 and FS5) are dispo/sed in. the well known manner for connecting trunks from the banks ot second selectors. r1`hatl is to say, the trunks to the 'local third selectors and to the incoming third selectors in the satellite lead from the banks of' the first selectors of the present invention as it' it were a local secondt selector iii well known systems, while the inter-office trunks lead from the banks of the said first selectors to incoming second selectors as heretotore practiced; the local second selectors being dispensed with.

1t' the first digit. sent does not cause spring set 121 or spring set 151 to operate; that is, it the first digit is not 4 to correspond to the ten-tliousaiid group containing the concerned first selector, and also is not 2 or I5 to correspond to the other ten-thousand groups of the system, the interrupter relay 1232 will not be caused to operate, so that the indicated tone source will be sustainingly applied audible to the calling part-y, as if the digit sent was the result of a false or so-called preliminary series accidentally introduced. ln view of previous descriptions, it is manifest. that when first selector FS (or FS?) is operated as last described, the vertical magnet is disabled through the retraction of lower armature of relay 117 and the disengagmg of spring 116, so an impulse applied from the armature of line relay 101 will not he thereafter effective unless the call has first been effaced.

lt, will be manifest that other levels than the. second and third shown may be set apart for the inter-office trunks to incoming second selectors of respective numerically corresilionding ten-thousand groups, correspondiiigly limiting the capacity of the ten-thousand group to which the concerned first seminera lector belongs. Moreover, this limiting of capacity will concern all other ten-thousand groups of the system having first selectors from which trunks of two numerical orders lead, as to incoming second selectors and to local third selectors, since trunks will (as shown) mutually lead from all tirsteselectors to incoming second selectors ot all t.enthou sand groups.

The trunk arrangement commonly practiced shown in Fig. 3, may be employed where the ultimateV ten-thousand group capacity is required subsequently.v That is, to change the f1 ten-thousand group to correspond to the well known trunking practice disclosed in Fig. t), a group of selectors like FS?l will lie substituted for the group of selectors like FS. Then, Vthe local trunks which lead-out from the levels of the group ot selectors to which selector FS belonged,

will be attached to corresponding levels of a group of' newly installed local second selectors of the same type as the said newly installed first selectors. 'llhe inter-office trunks will' be connected to levels of the newly installed first selectors to correspond to the former connection. Then, local trunks will lead from the corresponding level of the said newly installed first selector group (the fourth in the present instance) to the said newly installed second selectors. rll`his will apply to all local trunk levels of the first selector.

The present `invention thus lends itself where a multi-oflice'systein is desired, but wherein the ultimate capacity of ten-thousand lines in' one or more of the offices or .so-termed tenthousand groups is not required to be more than ten-thousand, less as many thousands as the number of ten-thoiisand groups employed in the system other than the office concerned.

The operation of the first selector FS2 will be clearly understood in the light of the foregoing detailed descriptions relating to first selector FS, having in mind that tlie coi're spoiiding parts shown in first selector FS`` are similarly designated as in first selector FS, but with a prime added, and that the parts shown in first selector FS'Z cooperate with parts (not shown) which are like the corresponding cooperating paits in first selector FS. However, a mechanical detail of selector FS2 is modified wherein an added wiper 201 and cooperating bank contacts are substituted for the spring sets 121 and 151 of selector FS. 'llhe tirst selector FS2 is located in the 2 ten-thousand group, the third and fourth bank levels thereof having interoflicc trunks lm and n leading therefrom to incoming second selectors l and H, respectively, of numerically corresponding ten-thousand --groups, and the second level having local trunks leading to local third selectors, as selector F. )Viper 201 normally engages a bank contact at each level position of the l with the second bank level responsive to sending first digit 2 in calling telephone T2',

for instance, a circuit will be completed from grounded conductor 109', armature 122', up per set` of vertical olf-normal springs, conductor a', wiper 201, bank contact 202, cond-uctor b', armature 123', lower vertical offnormal spring set to the release magnet (not shown) to lock the double-dog 124' and to restore the shaft to normal to cause the relay 132 to actuate and lock as described wlth reference to selectorFS. The next (second) erate spring set RON' so that the automaticdigit 27 sent will then reoperatethe shaft SH and set the wipers thereon into alignment-with the second bank level, corresponding to local trunks. The release magnet will not now operate, due to armature 123 being attracted.

The rotary magnet, designated Rot. M'., will operate to advance the wipers 118 to 120 over the second level in automatic selective or hunting operation, incidentally closing the rotary off-normal spring set RON' for the obiect described with reference to spring. set RN in selector FS.

.Had the shaft of selector FS2 been primarily operated with relation to the third or 'fourth level (corresponding to inter-oflice trunks), the relay 132`l would have actuated and locked from ground applied from conductor 109', armature 122', upper set of'vertical voff-normal springs, conductor a', wiper 201, bank contact' 203 or 204, conductor c' to the winding of relay 132', and the ground from grounded conductor 109' will bethen also applied through armature 122', springs 127 '-128', armature 139 to the rotary magnet to rotate the wipers 118' to 120 and opselective or hunting operation may continue as described with relation to selector FS when functioning on the second and the third levels.

It will be manifest that if the shaft of selector FS2ris set-with .relation to levels not numerically c rresponding to a ten-thousand group '(the fiy th level, for example), no circuit will be completed lto energize the interrupterrelay 1,32', so the shaft will be thereupon disabled from thereafter rotating-in or being raised-vertically in the manner s et forth with respect to selector FS.

Local `calls through selector FS2 to telephone T2, T2', and T will be completed by first setting the shaft lof selector FS2 intoalignment with the second level, from which position the shaft will be automatically restored, since selectdreFSz' is inthe 2 teni thousand group. Then, yannexing the lastfourgdigits of the corresponding telephone.v

number, dependingupon which 'telephone is called, will ycomplete the call, the operation Ifrom a calling line through any of the xtending a call from telephone T3 tov telephone T3 will be effected in the well known manner in view of the present invention) by successively operating first selector FS3 to the 'third level; local second selector J to the second level; third selector P to the third level;` and connector V to the second level and then in one step. It will be noted in this connection` that The interi-olflce trunks p and g vlead from the fourth and second' levels of selector FS3 to incoming second selectors K and L, respectively; that third selector A in Fig. 1 is accessible from the fourth levels of incoming second selectors H and K in a call over either of the inter-office trunks nl and p; that connector S in Fig. 2 is accessible from the lifth levels of incoming second selectors C and L and the second level of selector E; that third selector G in Fig. 2 is accesible fromthe first levels of incoming second selectors (land L; and that connector T is accessible from the third level of third selectors G and G.

Selector FS? is generally like the selector shown on page in the cited book by Hershey, so that its normal operation need not be detailed for a complete understanding of its general operation. However, the present invention comprehends the addition of two armatures on relay 317 an indicated tone source and circuits associated with the said armatures drawn slightly heavier than other control circuits to distinguish them. The operation as contemplated by the present inven-v is hunting, the armature 313 .ofi v line relay 301 will apply ground througharmatures314,5 315, winding of relay 317 to d10 the vertical magnet, armature 353 attractin to lock -relay l 317 from battery derive through the vertical magnet, resistance 354, rotary olf-normal spring set RO, ,winding of tone transformer 355 to ground. The re'- sistance 354 will restrict the'current below the operative value of the vertical magnet, but not below the sustaining requirement of relay 317. The tone will' be applied through armatures 356 and 306, audible to the callingparty,

indicative of the condition. Armature7322 being attracted, operatively energiz'es the wind'- ing of relay 332, so that armature 336 applies N 'ground to the upper winding terminal of. switching relay 343 to maintain it disabled. The attracted armature 322 also disables the rotary magnet. That is, if armature 313 retracts while selector FSs is hunting, the selector will become disabled from thereafter hunting, or of seizing by the actuation of re- Jthe concerned selector of the connection is hunting.

By joining the sheet containing Fig. 6 to the right ofthe sheet containing Fig. 5 so that the linesextending to the adjacent margins register, and then substituting the sheet containing Fig. 5 (while attached lto the sheet cointaining Fig. 6) for the sheetcontaining Fig. 1

` a preferred organization is attained. It will be noted that calls tothe telephones shown on sheets containing Figs. 2 and 3will be reached over the same inter-oilice trunks from the sheet containing Fig. 5. Also, that the telephone '1'5 may he reached over switch links of Fig. 5 corresponding' to switch links B, R, M, K and ll, shown in Fig. l, used in connecting to telephone l, having in mind the corresponding links have a prime added to their desi., ation letter. 'llhe trunks j, 22:5, fn. and p in ig. 5 correspond to j, 76,1 and p in Fig. l, respectively. Designation numerals in Fig. 5 correspond to similarly disposed parts in Fig. l, but have digit 5 for the first digit in lieu of llt Y rllhe general operation of selector F85 will loe understood from the descriptions with respect to Fig. l. However, the modifications will loe explained in view of their objects.

rll`he ten-thousand group containing selector F55 has'a satellite or sub-oce located in a building remote from the building containing selector FSE. That is, the' thousands groups'of trunlrsleading from the fourth and the fifth levels of selecterl FS5 (and its'companion selectors) representedby trunks/w and are inter-subpce trunk groups rather than 45" local trunk groups, as are the trunks leading .from the fourth level of selector FS, wherein s lector lfrepresents a group of local third The trunks w and -@may eachihavea-well known so-calledntrunlr repeater' .interposed at the originating end, to translate from three-con-V duct/or to two-conductor operation for the' inter-choc section. The calling of a num-f loer from telephone 'F5 will causethe selector F55 to operate the saine in selecting on level l or levels el and 5, having in mind that eight levels (lacing all but the second and third levels used for inter-mainoeice trunks) may loe interchangeably used for local or satellite connections wit `out altering the selector lfunctiruuil operation. i

ls-understood from statements made at the outset, the selector FS will loe employed where the localand satellite capacity cornhlned for the tenethousand group containing selector FSl5 will not exceed eight thousands; divided as the exchange layout. warrants.

sive to the said first digit, will determine if the call will be extended to the satellite or will be a local one; the same number of switch links being employed in either instance, since it will be noted that the trunks fw and terminate in incoming third selectors W and X, respectively. r

ln the last exampled instance, the shaft SH5 will be automatically restored if primarily aligned witheither the :fourth orthe fifth level, o that pulling an initial digit 4 or 5 wlll have the same operative value and effect and may therefore be pulled interchangeably where the listed number has digit el or 5 as the first digit thereof. This is provided, as adverted to at the outset, so that the first digit of the calling number will be specific` to the lines 'directly tributary to the buildingcontaining selector FS and to the building containing the satellite, respectively.

0f course, it will understood that the trunk group represented by trunks w and .fr may each (group) refer to a specific satellite, in. place of both referring to the same satellite. 'fhat is, inplace of the satellite having a capacity of two thousand lines, two satellites of one thousand lines each may loe concerned. Moreover, each of the levels above the fth may refer to a specific satellite of one-thousand lines capacity or a lesser number of satellites with a total capacity f five thousand llines in Vlevel combinations as arbitrarily chosen and combined". And, infact, level l may refer toa satellite of one-thousandlines capacity.A l

.The exampled instancejassumes that the satellite corresponding to the fourth and the fifth levels may at a future time be converted into amain orten-thousand group. At such time, the shaft projection g5 will be moved on the shaft to operate spring set 551 in lieu of springfse't 1521. Then, a group of interoflice trunks leading to incomingsecond se'- lectorshaving access to hoth the third selector digit, if the selector restores its shaft respongroups'rW and l will'be substitutedl for the. n

satellite trunks jug and Under this chndi tion the latter. said substituted inter-,oce trunks will lead from the fifth level, thus leaving the fourth'level of selector FS5 dead and available for local one-thousand' capacity,

level not chosen for inter-office trunks may be introduced on the shaft 55H5 so the shaft may then loe operated with relation to the fourth level or with relation to the 1said chosen level, to cause the selector FS5 to release and then be operated over a level other than inter-'oiiice trunk levels (but including the s fourth and the said chosen level)` to reach a local or satellite' level interchangeably, for the object set forthwith reference to the fourth and fifth levels wherein projections @Fand 2/5 are employed.

lIt will be clear, from the-foregoing,that in calling .telephone TG or telephone TG, the first digit may be either 4 .or 5 interchangeably. Further, since they refer to the 5 ten-thousand group of numbers, they may be segregated by introducing a group incoming second selector antecedent to selectors W and X leading from the iifth level of selector F55; the projection g5 being changed to operate spring set 551 at'the fifth level position of the shaft SHS. It will also be clear, in this connection, that any otherlevels above the fifth could have been chosen for the trunk groups w and w without changing the projections d5 and g5, butin that event the thou- 25 sands 'of the satellite reached over the trunks w and m will numerically correspond to the last said levels of selector FS5 chosen.

It will be noted that the relay 517 is included in a path directly from the make contact of armature 515, in lieu of through a spring corresponding to 116 in Fig. 1. In the event the armature513 of line relay 501 is caused to 11e-- tract while the selector F85 is hunting,

ground will .beV applied through armatures '514, 515, winding of relay 517 to the vertical magnet, effective to attract armature553. A locking circuit of relay 517 will be established throughthe vertical magnet, winding offrelay 517, resistance 554, armature 553, rotary off-normal springs of set R05 to interrupted ground source 555. The resistance 554 is vof such value as will restrict the'current below the operative' value of/the 'vertical magnet,

but not below lthe su'stainingvalue of-relay 4517. A' Ilie interrupted vground 'will s'erve'to maintain therelay y,517 actuated (due toits characteristic of sustaining over brief current lpses', because ofbeing slow-releasing) and I 'a thesame time apply'the-interrupted ground through armature's548 and-506,audib-leto the calling party, indicative' of'the condition. y.Under t is condition, armature522 applies 4ground to the conductor leading to the upper#- 'winding terminal of relay 543 to maintain Ait disabled, so the selector cannot seize the rotary magnet being disabled due to the attracted condition of armature 522.

The tonesource shown in Fig. 5 is applied throughspring set 547, armatures 557, 548l --and 506, audible tothe calling party, if the shaft SH5 is raised so its wipers align with a level at which sp-ring'set 551 or 521 is not operated to cause relay 532 to actuate and lock. That is, since springn set 547 will close at off-normal vertical positions, unless the operation of the selector has been normal,

armature 557 will remain retracted after armature 522 reti-acts to cause a sustained tone application audible to the calling party. A

brief tone application before the armature 557y will be clear in view ,of the citation. The I modification of the connector contemplated by the present invention is indicated by the lines drawn slightly heavier than other operating conductors to distinguish them.` When the connector C6 is selectively set upon a busy called line theindicated apprisingl tone source will be applied through arniaturesl,4 602, 603, wiper 604 to the engaged bank contactof the called line, audible to the user thereof'to indicate the condition. The detailed operation is as follows: Relay B', which is the sfo-called busy relay, actuates consequent to the test wiper 605 encountering busy-,ground in thetest contact, which closes the last described tone path and maintains it until armature 602 retracts, the releasing period of relay A after the impulses v.to the rotary magnet cease. The

' switch-arm 606 may be manually set to apply grounded battery through retardation coil -of relay B in opposition to the upper winding so when the wiper 605 passesover busy grounded bank contacts in reachingthe test Acontact ofthe called line the lower winding will energize to tend to prevent the operative attraction of larmature 601. The saidlow'er Winding will not-in itself operatively attract armature 601, due to the adjustment of arniat'ure601, but it eXerts-sutci'ent tractive effort to prevent the upper winding doing so. However, after the wiper605 isset upon a busygrounded bank contact for -a slightly proonged period, -thelower winding 4of relay'B being then unenergized, the yupper windingwill operatively'.'energize. The z conductor leading fromarmature 609 includes'La set of i able' relay -B from. operatingv while passing over busy-grounded bank-'contacts'to the busytestcontact of theline under call. This is to insure that disturbance will not be applied tov a passed-overbusy line. It will thus be clear laddednorlnally 'closed vcontacts 610; operat-` ,.1 i edby thearmatiire otthelrotary magnet, 'censequent toits initial movement to' furthe-r' disthat a brief tone, ora tone vandbatt'ey-click,

vwill be applied audible to the user vof a busy called line, upon a connector being operated into testing relation therewith and finding it barred. It will be manifest that the relay Cil B may be given a slightly stiff adjust-ment.

-lshaft is. in its operationfrom normal or its restoration to normal. When it is at normal, the double-dog is locked bythe release link 126. The object of this provision is to permit the shaft to restore freely, due to the said spring sets being -flexed out of line with the said shaft projections.

In the foregoing, a so-called hundred-thousand line orfivedigit ultimate capacity system was contemplated. It will be manifest that the present invention can be also applied to other capacity systems; so-called fourdigit or ten-thousand rline ultimate capacity systems, for example. The application of the present invention to the four-digit system would be as disclosed with reference to the live-digit system, assuming that the interoiii'ce trunks would extend to second selectors having direct access to connectors, and that local trunks from the rst selectors would eX- tend to connectors, there being-no third selectois i plication ofthe invention, the levels below the fourth, for instance, will not be subject to selection, unless the shaft of the selector is first operated with relation to the third level vand restored through the agency of the projection (Z, set to operate the spring set 121 at the third level. The Contact set 151 will then be adjusted to be operated at all levels above the third.. This will entail five-digit numbers where a line under call is reached over a level below the fourth. 'lhe first digit 3 will be e'ed tive to operate and restore the shaft and actuate and lo'k the relay 132, preparatory to a i l level-hunting operation responsive to the second digit being sent to reoperate the shaft into alignment with a level below the fourth. That is, it will vbe necessary to send a preliminary digit f to capacit-ate the first selector for hunting over a level below .the fourth.

vManifestly, this may be applied to so-called hundred-thousand line systems, Under this application the levels below the fourth cannot -be hunted over unless a preliminary digit 3 has been sent as before; making six digits in all. Of course, any other level than the third may be chosen, but to gain the advantages of the function it should be above the the selector is connected with for causing the operation of the relays'to set the selector into hunting relation to the line terminals and seize the first idle one encountered, and relay operated means comprising only said relays for disabling the selector from seizing responsive to the control means being operated while the selector is hunting.

2. ln an automatic telephone system, a Wiper selector, switch means for connecting to the selector, relays of the selector, -a group of line terminals accessible from the selector, remote' control means operated at will after the selector is connected with for causing the operation of the relays `to set the selector into hunting relationto the line terminals and seize the first idle one encountered, and relay operated means comprising only said relays for disabling the selector from seizing ree, sponsiveto the control means being operated while the selector is hunting.

3. ln an automatic telephone system, a wiper selector, switch means for connecting to the selector, relays ofthe selector, a group ofline terminals accessible from the selector, remote control means operated at will-after the selector is connected with for causing the opi iol eration of the relays to set the selector into Y ergizing and deenergizing of the relays to set the selector into hunting relation to the line terminals and seize the lfirst idle one encountered, and relay means comprised only of said relays for disabling the selector from continuing its hunting operation responsive to operating the control means while'the selector is hunting.

lltl

- and relay means comprisedV only of said rep lays responsive to the control means for stoppingtthe hunt-ing operation without restoring the selector.

6. In an automatic telephone system, a calling lirne, a selector terminating the calling line, switch means for connecting to the calling line, relays for operating the selector, a group of line terminals accessible from the selector, control means operated over the calling line at will-only after the calling line is connected with by the switch means for causing the operation of t-he relays to set the selector into hunting relation to the line terminals and seize the first idle one encountered, and relay means comprising only said relays operated for disabling the selector from seizing responsive to the cont-rol means being operated while the selector is hunting.

7. In a telephone system, a calling line, a selector terminating the calling line, switch means for connecting to the calling line, re-

lays of the selector, a group of line terminals accessible from'the selector, direct-ive control means on the calling-line at will only after the calling line is` connected with by the switch y means for operating certain of the relays to set the selector with selective relation to the group, means for causing certain of the relays to thereafter operate the selector in hunting relation with the group and seize the first idle terminal found, and relay means'comprising only said before operated relays operated for disabling t-he selector from seizing responsive to the control means being operated while the selector is hunting.

8. In a telephone system, a calling line, a selector terminating the calling line, switch means for connecting to the calling line,l re-v lays of the selector, groups of line terminals accessible from the selector, directive control means on the calling line at will only after the calling line is connected with by the switch Y means for operating certain of the relays to set the selector with selective relation to a desired group, means forv causing certain of the relays to thereafter operate the selector in hunting relation with the group and seize the first idle terminal found, and relay means comprising only said before operated relays operated for disabling the selector from seizing responsive to the control means being operated while the selector is hunting.

9. In a. telephone system, a switch, primary and secondary driving magnets for the switch, groups of line terminals accessible from the switch, automaticmeans for direc-r tively operating the primary magnet to set the switch with selective relation to a desired group, means for then operating the secondary magnet for causing the switch to hunt over the terminals of the selected group, directively controlled means including the primary magnet operated before th first said operation for rendering the huntmg operation automatically applied responsive to the first said operation, and means for normally rbarring the switch from operating4 its secondary magnet untilfthe last said means isoperated.' v

10. In a telephone system, a switch', primary and secondary driving magnets for the switch, a group of line terminals accessible from theswitch, automatic means for operating the primary magnet to set the switch with selective relation to the group, means for operating the secondary magnet for causing the switch to hunt over the terminals of the group, directively controlled means including the primary magnet operated'before the first sa1d operation for operating and restoring the switch for rendering the hunting operation automatically applied responsive tothe first i switch, a group of line terminals accessible from the switch, automatic means for oper.- ating the primary magnet to drive the switch with selectiverelation tothe group, means for causing the secondary magnet to `operate to drive the switch with'connective relation to the first terminal of the group, Aand di-` rectively controlled means operatedbefore the first said operation for rendering the secondary magnet responsive to automatically applied means to drive the switch responsive to the first said operation.

12. In a telephone system,a switch,primary and secondary driving magnets for the switch, a group of line terminals accessible from the switch, automatic meansfor operatingthe primary magnet to drive the switch with se.-

lective relationto the group, means for causing the secondary magnet to operate to drive the switch with connective relation to the first terminal of the group, directively controlled means operated before the first said operation for rendering the secondary magnet responsive to automatically lapplied means to drive vthe switch responsive to the first said operation, and means for maintaining the swltch in the first said operated condition if the d1- rectilvely controlled meansis not operated.

, 13. In a telephone system, a switch, primary and secondary driving` magnets forthe switch, -a group of line terminals accessible from the switch, automatic means for operating the primary magnet to drive the switch` with selectiverelati'on to the group,means magnet responsive to automatically applied means to drive the switch responsive to the first said operation, and means for maintai-ning the secondary magnet of the switch disabled from operating if the last said means is not operated.,

14. -n a telephone system, a switch, primary and secondary driving magnets and a release magnet for the switch, groups of line terminals accessible from the. switch, automatic means for operating the primary mag-v net to set the switch with selective relation to a desired group, means for operating the secondary magnet for causing the switch to hunt over the terminals of the selected group, directively controlled means including the primary magnet and the release magnet operated before the lirst said operation for operating and restoring the switch and for rendering the hunting operation automatically applied responsive to the first said operation, 'and means for maintaining the switch in the first said operated condition if the last said means is not operated,

15.. ln a telephone system, a switch, primary and secondary driving magnets and a release magnet lfor the switch, groups of line terminals accessible from the switch, automatic means for operating the primary magnet to set the switch with selective relation to a desired group, means for operating the secondary magnet for causing .the switch to hunt over the terminals of the selected group, directively controlled means including the primary magnet and the release magnet operated before the irst said operation for oper,-

ating and restoring the switch and for ren dering the hunting operation automatically applied responsive to the first said operation, means for maintaining the switch in the first said operated condition if the last said means is not-operated, and fia signal device rendered operative consequent to the said disablement.

16. In a telephone system, a switch, primary and secondary driving magnets and a release magnet for the switch, groups of line terminals accessible from the switch, automatic means for operating the primary magnet to set the switch with selective relation to a desired group, means for operating the secondary magnet for causing the switch to hunt over the terminals of the selected group, directively controlled means including the primary magnet and the release magnet operated before the first `said operation for operating and restoring the switch'and for rendering the hunting operation automatically applied responsive to the first said operation, and means for disabling the secondary magnet from operating if the last said means is not operated.

, 17. In a telephone system, a switch, a plurality of groups of line terminals, primary and secondary -driving magnets for the switch, automatic means for directively operating the primary magnet to drive the switch into selective relation to a desired said group, automatically applied means for causing the secondary magnet to drive the switch over the terminals of the selected group, and means depending upon what group the switcliis driven into selective relation to for thereupon disabling the secondary magnet from thereafter operating.

18. ln a telephone system, a switch, a pluf thereupon disabling the secondary magnet l from thereafter operating, and a signal device rendered operative consequent to the said disablement@ 19. ln a telephone system, a calling line, a tone source, a calling device on the calling line, a switch, a plurality o f groups of line i terminals, primary and' secondary driving magnets for the switch, automatic means' for directively operating the primary magnet to drive the switch into selective relation to a random said group,automatically applied means for causing the secondary magnet to drive the switch over the terminals of the said selected group, and means depending u on what group the switch is driven into said selective relation to for thereupon disabling the secondary magnet from thereafter operating and for applying the tone source to thecalling line.

20. ln a telephone systemaswitch, a plurality of groups of line terminals, primary and secondary driving magnets for the switch, directive means for automatically operating the primary magnet tof drive the switch into selective relation to a random said group, automatically applied means for causing the secondary magnet to drive the switch over the terminals of the selected group, means depending upon what group the switch is driven into said selective relation to for thereupon disabling the secondary magnet from there-v after operating, and means dependent upon operating the switch by the primary magnet to a predetermineds group for disabling the last said means. Y

y21. In a telephone system, a switch,'a plurality of groups of line terminals, primary and secondary driving magnets for the switch,

pending upon what group the switch isdriv-` f en into said selective relation to for thereupon disabling the secondary magnet from thereafter operating, and means dependent upon operating the, switch by the primary' magnet to one or another of a plurality of predetermined levels before the first said operac tion for disabling the last said means.

22. In a telephone system, a' switch, a plu; rality of groups of line terminals, 'rimary and secondary driving magnets or the switch, directive means for automatically operating theprimary magnet to drive the switch into selective relation to a random said group, automatically applied means for causing the secondary magnet to drive the switch over the terminals of the selectedgroup, means depending upon what group the switch is driven into selective relation to for thereupon disabling the secondary magnet from thereafter operating, and means dependent upon operating the switch by the primary magnet to a predetermined group before the first said operation for disabling the last said means. Y

23. In a telephone system, a switch, a plurality of groups of line terminals, primary and secondary driving magnets and a release magnet for restoring the switch, directive means for automatically operating the primary magnet to drive the switch into selective relation to a random said group, automatically applied means for causing the secondary magnet to drive the switch over the terminals of the selected group, means depending upon what group the switch is driven into selective relation to for thereupon disabling the secondary magnet from thereafter operating, and means dependent upon operating the switchby the primary magnet to a randol one of a plurality of predetermined groups of said line terminals to thereupon automatically,operate the release lmagnet responsive to attaining the selected group to restore the switch before the irst said operation for disabling the last said means.

v24:. In a telephone system, a switch, levels of trunk line terminals of two numerical orders .accessible from the switch, means for operating the switch in correspondence with the numerical orders, respectively, to select a trunk line of a corresponding numerical order level, and meansy for thereafter barring the switch from seizing a trunk of a selected level of one said numerical orders responsive to the switch being selectively operated with respect to i a level in accordance with the other numerical order.

` 25. In a telephone system, a switch, groups of trunk line terminals of two numerical orders accessible from the switch, means for operating the switch in correspondence with the numerical orders, respectively, to select a trunk line of a corresponding numerical'order group,and means for thereafter barring `the switch from seizing a trunk of a selected der group, and means for barring the swit'ch from seizing a trunk of a selected group of one said numerical orders and for applying a signal responsive to the switch being selectively operated with respect to a group in accordance with the other numerical order.

27. In a telephone system, a switch, a plu-A levels, belonging to specific numerical orders,

means for operating the switchinto selective relation to a random one of the levels and in hunting relation thereover, means for operating the switch with specific correspondence with the numerical orders, and means for thereafter maintaining the levels of one nu- Vmerical order barred to the hunting' operation of the switch unless a level of the last said levels has been selected by a corresponding numerical order operation.

28. In a telephone system, a switch, a plurality of groups of trunkterminals, specific groups'belonging to specific numerical orders, means for operating the switch into selective relation to arandom one of the groups and in'hunting relation thereover, means for operating the switch with specific correspondence with the numerical orders, and

means for thereafter maintaining the groupsl of one numerical order barred to the hunting operation of the switch unless a group of the last said groups has been selected by a corresponding numericaLorder operation.

29. In a telephone system, a switch, a plurality of levels of trunkterminals, specific levels belonging to specific numerical orders, means for operating the switch in selective relation to random said levels and in automatically applied hunting relationthereover, means for operating the switch with selective relation to a said level in correspondence with one or another of said numerical ordersat will, and meansqfor thereafter maintainmg the levels of one numerical order barred to a hunting operation of the switchunless f the said level when selected has been selected by a correspondmg numerical order' operation.

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